Norwegian Cruise Line Holdings plans to start sailing its fleet throughout the world in July, despite Washington's refusal to lift restrictions on cruiseships operating in US waters.

TradeWinds reported on 24 March that the US Centers for Disease Control and Prevention (CDC) refused a call to lift an order restricting cruises by early July, nearly four months ahead of schedule.

The year-long Framework for Conditional Sailing Order, which replaced a no-sail order for cruiseships in US waters, set out rules effective to the end of October this year that include mock voyages and onboard virus testing labs.

But Norwegian, the owner of 28 ships across brands Norwegian Cruise Line, Oceania Cruises and Regent Seven Seas Cruises, announced on Tuesday a "two-pronged approach" to resume sailing from US ports on 4 July — American Independence Day.

It will also start sailing ships from Jamaica, the Dominican Republic and Greece with three Norwegian Cruise Line ships.

The company asked the CDC to lift the conditional sailing order and said the first voyages will operate with fully vaccinated guests and crew.

The Miami-based cruise giant has formed a SailSafe programme requiring pre-sail Covid-19 testing and a SailSafe Global Health and Wellness Council, led by former US Food and Drug Administration commissioner Dr Scott Gottlieb.

'Why can't we sail?'

Norwegian chief executive Frank Del Rio questioned why the CDC is adamant about keeping the sailing restrictions.

“I’d like to hear an argument why we couldn’t sail,” Del Rio said in an interview with the Washington Post this week.

“If everyone on board is vaccinated and following the protocols, there is absolutely no need for the conditional sail order to exist as it is known today.”

On Monday, the Cruise Lines International Association (CLIA) called on the CDC to lift the conditional sailing order this month.

On 2 April, the CDC laid out the order's first phase of instructions, which still require the simulated sailings.

"The new requirements are unduly burdensome, largely unworkable and seem to reflect a zero-risk objective rather than the mitigation approach to Covid that is the basis for every other US sector of our society," the CLIA said.

"The effect of these new mandates is that nearly half a million Americans — from longshoremen and ground transportation operators to hotel, restaurant and retail workers, travel agents and tens of thousands of businesses that service cruiseships — are continuing to financially suffer with no reasonable timeline provided for the safe return of cruising."

The association also said the CDC rules are "at odds" with the agency's approach to other travel and tourism industries, which have received relaxed guidance due to vaccination progress.

Florida governor Ron DeSantis has reportedly threatened to file a lawsuit if cruises continue to be blocked this summer.

The US Travel Association, which also represents the airline sector, is urging the CDC to lift the order.

Calls to the CDC were not returned.

Greece has given Carnival brand Seabourn permission to sail from its shores on 3 July.